Optimization of network signaling load and/or user equipment power consumption in a packet mobile system

ABSTRACT

In an embodiment, there is provided a method for optimization of network signalling load and/or User Equipment power consumption in a packet mobile system wherein an User Equipment UE has access to a network comprising a Core Network CN accessed by a Radio Access Network RAN, a method wherein CN assistance information is provided by said CN to said RAN for an UE, said CN assistance information including information determined in said CN based on a learning by said CN of a traffic pattern and/or a mobility pattern of said UE, and said CN assistance information is used in said RAN to adjust RAN parameters enabling to control transitions between idle and connected state and/or power consumption in connected state for said UE.

The present invention generally relates to mobile communication networksand systems.

Detailed descriptions of mobile communication networks and systems canbe found in the literature, such as in particular in TechnicalSpecifications published by standardization bodies such as for example3GPP (3^(rd) Generation Partnership Project).

In general, in such systems, an User Equipment (UE) has access to amobile network comprising a Core Network (CN) accessed by a Radio AccessNetwork (RAN).

Examples of packet mobile communication systems include EPS (EvolvedPacket System), UMTS, . . . etc.

EPS network, for example, comprises a Core Network called EPC (EvolvedPacket Core) that can be accessed by a Radio Access Network calledE-UTRAN. An example of architecture of EPS network is recalled in FIG. 1(taken from 3GPP TS 23.401), showing the main network nodes andinterfaces between network nodes. Interfaces between EPS network nodesinclude, in particular, Uu interface between UE and E-UTRAN node calledeNodeB (eNB), and S1-MME interface between eNB and EPC node calledMobility Management Entity (MME).

Control plane signaling may be exchanged on the Uu interface between UEand eNB, and on the S1-MME interface between eNB and MME, duringsignaling procedures. Signaling procedures include, in particular,signaling procedures performed at UE state transition (such as servicerequest procedure performed at transition from idle to connected state,or signaling connection release procedures performed at transition fromconnected to idle state), mobility procedures (such as handoverprocedure performed in UE connected state, or Tracking Area Updateprocedure performed in UE idle state). An UE may transition fromconnected state to idle state if there is not enough UE activity in theuser plane, or from idle to connected state if there is again UEactivity in the user plane. RRC signaling protocol between UE and eNB isdefined in particular in 3GPP 36.331. S1-AP signaling protocol betweeneNB and MME is defined in particular in 3GPP TS 36.413.

New types of communications, such as Machine Type Communication (MTC) orother mobile data applications communications (e.g. Instant MessagingIM, social networking applications, . . . etc.) are becomingincreasingly used. Such new types of communications have new servicerequirements, such as frequent small data transmission, frequent UEstate transitions, . . . etc. New functionalities are therefore neededfor the support of such new service requirements, such asfunctionalities to efficiently support increased control plane signalingwith minimal impact on the network and on the UE power consumption, . .. etc. More generally, network and system optimizations are needed forsuch new types of communications.

Embodiments of the present invention in particular address such needs.

These and other objects are achieved, in one aspect, by a method foroptimization of network signalling load and/or User Equipment powerconsumption in a packet mobile system wherein an User Equipment UE hasaccess to a network comprising a Core Network CN accessed by a RadioAccess Network RAN, a method wherein CN assistance information isprovided by said CN to said RAN for an UE, said CN assistanceinformation including information determined in said CN based on alearning by said CN of a traffic pattern and/or a mobility pattern ofsaid UE, and said CN assistance information is used in said RAN toadjust RAN parameters enabling to control transitions between idle andconnected state and/or power consumption in connected state for said UE.

These and other objects are achieved, in other aspects, by entitiesconfigured to carry out such method, said entities including, inparticular (though not exclusively), RAN entity (such as eNB forE-UTRAN, or RNC for UMTS), CN entity in charge of control plane (such asMME for EPC, or SGSN for UMTS), CN entity in charge of user plane (suchas Serving Gateway S-GW or PDN Gateway P-GW for EPC, or GGSN for UMTS).

Some embodiments of apparatus and/or methods in accordance withembodiments of the present invention are now described, by way ofexample only, and with reference to the accompanying drawings, in which:

FIG. 1 is intended to recall an example of architecture for EPS network,

FIG. 2 is intended to recall an example of timing for an UE experiencingfrequent idle-active mode transitions,

FIG. 3 is intended to illustrate, in a simplified way, an example ofprocedure based on the use of CN assistance information according toembodiments of the present invention.

Embodiments of the present invention will be more detailed in thefollowing, by way of example for 3GPP systems such as EPS. However itshould be understood that the present invention is not limited to EPS,and could apply as well to systems other than EPS (for example UMTS, orsystems specified by standardization bodies other than 3GPP).

3GPP SA2 is in the process of studying enhancements for machine-type andother mobile data applications communications (3GPP release 12, see 3GPPTR 23.887). Many mobile data applications (e.g. always on mobile dataapplications such as IM or social networking applications, etc.) arecharacterized in particular by transmission of small and bursty datapackets (i.e. in terms of packet size) in the UL and DL, e.g.

-   -   status update messages to notify the users of status updates        relating to the application, e.g. applications such as FindMe        generate status update messages upon geographic position changes        up to every 60 seconds;    -   periodic keep-alive messages to keep the application session        alive and also to avoid the expiry of NAT mapping which causes        IP session disconnection,    -   presence information of buddies in an IM buddy list,    -   update of user location upon user “check in”,    -   update of “Facebook likes” to a user's friends, etc.

Bursty data transmission may cause the UE to transition frequentlybetween idle and connected state, if the UE is sent to idle mode soonafter the transmission of the data is complete. If the UE is kept inconnected mode for an extended duration it has impact on UE powerconsumption and more extensive control plane signalling is required forhandovers. This is depicted e.g. in FIG. 2 corresponding to FIG. 2 of3GPP TR 22.801 (non-MTC Mobile Data Applications impacts) clause 5.2.

Such frequent transmissions can have the following adverse effects onthe network and the UE:

-   -   Increased control plane signalling in RAN (Radio Access Network)        and CN (Core Network);    -   Increased UE power consumption.

RAN2 studies in 3GPP TR 36.862 analyse in particular the effects of theRRC inactivity release timer & the DRX (Discontinuous Reception) cycleon network signalling (transitions idle<>connected), handovers (extrahandover signalling when keeping the UE in connected state for a longerRRC release timer, in particular for moving UEs), and UE powerconsumption, for different kinds of traffic. RAN2 also specified inRel-11 (see 3GPP TS 36.300 and 36.331) a new UE assistance informationprocedure enabling the UE to indicate to the network a power preferenceindication, e.g. lower power consumption, to enable the eNB to optimizethe setting of the DRX parameter & RRC (inactivity) release timer.

Solutions are now being investigated in 3GPP SA2 to reduce the highfrequency of signalling procedures, e.g. RRC signalling, paging/servicerequest procedures, caused by bursty data transmissions or frequent UEstate transitions.

S2-122787 (NEC, 3GPP SA2#92) proposed to monitor the traffic of the user(using a monitoring client in the UE and a monitoring server in thePLMN) to learn the traffic patterns of the user, store them in the HSSand re-use them to optimize the user inactivity timer used in the RAN.But the solution based on determination of individual applicationtraffic patterns is complex to design & deploy, requires UE changes(traffic monitoring client in the UE) and thus cannot be used withlegacy terminals, and further contribute to load the radio and corenetwork by requiring the UE to send extra traffic to the monitoringserver in the PLMN and requiring the latter to upload the trafficpatterns in the HSS.

Other solutions are being studied to minimize the number of keep-alivemessages the terminal sends e.g. by coordinating keep-alive messagesacross all the applications running on the UE or by delegating somekeep-alive control to the network. Although this will help reducing thefrequency of bursty data transmission for some applications, this willnot help for frequent bursty data transmissions caused for other reasonse.g. status updates, user location updates, presence information updates. . .

Embodiments of the present invention in particular enable to avoid suchdrawbacks or solve such problems.

In an embodiment, the Packet Switched Core Network (and in particularthe Mobility Management Control entities i.e. MME and SGSN) can provideassistance information to the radio access network (eNB for E-UTRAN andRNC for UTRAN) based on the learning of the traffic pattern (e.g. timebetween successive signaling connections, mobile originated or/andmobile terminated traffic) and/or the mobility pattern (e.g.static/nomadic vs moving user) of the user and/or user's subscriptionparameters (e.g. static/nomadic user), that enables the RAN toadjust/optimize the RAN parameters (DRX cycle, RRC user inactivitytimer) applied to the user and thus reduce the frequency of transitionsbetween idle and connected states, minimize network signaling and saveUE battery.

In an embodiment, the Mobility Management Control entities (i.e. MME andSGSN) are well aware of when signaling connections are established andreleased with the UE/RAN and can make use of this to monitor e.g.

-   -   the time elapsed between the release of the last signaling        connection and the establishment of the subsequent signaling        connection. A short duration (e.g. a few seconds) would be an        incentive for the RAN to increase the RRC user inactivity timer;    -   the frequency of transitions between idle and connected modes,        and detect offending UEs with abnormally frequent transitions;    -   whether or how frequently the traffic originates from the UE        or/and the network, e.g. whether this is an UE that only or        mainly utilize mobile originated communications. UEs with Mobile        originated only traffic or Infrequent mobile terminated traffic        could be configured e.g. with a longer DRX period to minimize        battery usage (since this would not add the adverse effect of        adding latency for delivery of mobile terminated traffic).

In an embodiment, the MME and SGSN can subsequently use theseinformations to pass information assisting the RAN (eNB or RNC) tooptimize RAN parameters and in particular the DRX cycle (i.e. period ofdiscontinuous reception when the UE is in connected state) and the userinactivity timer used in the RAN to release the RRC signaling connectionof the user , e.g. during the setup of the subsequent signalingconnection (e.g. in the S1-AP Initial Context Setup Request sent to theeNB).

In an embodiment, the RAN may additionally transfer assistanceinformation to the MME or SGSN during the release of the signalingconnection (e.g. in the UE Context Release Complete message sent by theeNB to the MME) e.g. the value of the RRC user inactivity timer appliedfor the signaling connection being released, for subsequent use duringthe setup of the next signaling connection of the user.

Following steps are illustrated in the example of FIG. 3:

-   -   On-going signalling connection between UE and MME via eNodeB,    -   Expiry of RRC user Inactivity Timer in eNodeB,    -   Message “S1-AP S1 UE Context Release Request” sent by eNodeB to        MME, containing a user inactivity cause,    -   Message “S1-AP S1 UE Context Release Command” sent by MME to        eNodeB,    -   Message RRC Connection Release sent by eNodeB to UE,    -   Message “S1-AP S1 UE Context Release Complete” sent by eNodeB to        MME, containing RAN assistance data for next signalling        connection,    -   MME stores date/time of S1 connection release and RAN assistance        data,    -   New small data available for transmission in UE,    -   Message “NAS Service Request” sent by UE to MME,    -   MME detects frequent transitions between idle and connected        states and notifies so to the eNB,    -   Message “S1-AP S1 Initial Context Setup Request” sent by MME to        eNodeB, containing RAN assistance data and CN assistance data,    -   Radio Bearer Establishment between UE and eNodeB,    -   Message “S1-AP S1 UE Initial Context Setup Complete” sent by        eNodeB to MME,    -   eNB adjusts the RRC user inactivity timer and DRX parameters to        reduce idle-connected transition frequency and optimize battery        usage.

In an embodiment, the MME/SGSN can also monitor the mobility pattern ofthe user, e.g. by monitoring mobility events (such as handovers,Tracking/Routing Area updates) over time, or thanks to possibly newsubscription data (e.g. flagging a static or nomadic user). The MME/SGSNcan also use these informations to complement the assistance informationpassed to the RAN (eNB or RNC), e.g. enabling the eNB to increase theduration during which it maintains a RRC signaling connection w/o useractivity for a static or nomadic user (as a handover would be quiteunlikely to happen for such a user).

In an embodiment, the MME/SGSN learn the traffic and/or mobilitypatterns of the user while the user is attached to the network. Tominimize impacts in the PS core network, the learned patterns would notbe forwarded to the new PS CN node (i.e. MME or SGSN) during inter-CNnode mobility, nor stored in the HSS.

Embodiments of the present invention do not require any change interminals, and are therefore usable with all UEs. Embodiments of thepresent invention require minimum changes to MME/SGSN while providingpotential for large network signaling and UE power battery savings.Embodiments of the present invention do not cause any extra traffic loadin the network just for the purpose of learning the user's trafficpatterns.

Embodiments of the present invention may be extended with other examplesof assistance information. Although it is preferred to rely only on theMobility Management Control entities, embodiments of the presentinvention could possibly be extended with assistance informationmonitored in other PS CN nodes, e.g. the SGW (i.e. anchor point of allthe PDN connections of the user under 3gpp access) or PGW, in which casethe information would be passed to the RAN either directly e.g. viaGTP-U extension headers or via the MME/SGSN (and S11/S4 signalling). Theassistance information could then possibly cover e.g. the applicationtype (detected in PGW), inter-packet arrival time (detected in PGW orSGW) . . .

Embodiments of the present invention provide a generic solution for allkinds of applications, simple to implement & deploy, usable with all UEs(i.e. including legacy smartphones), with the potential of significantnetwork signaling (in RAN and CN) and UE power battery savings.

In one aspect, there is provided a method for optimization of networksignalling load and/or User Equipment power consumption in a packetmobile system wherein an User Equipment UE has access to a networkcomprising a Core Network CN accessed by a Radio Access Network RAN.

Various embodiments are provided, which may be taken alone or incombination, according to various combinations.

In an embodiment, CN assistance information is provided by said CN tosaid RAN for an UE, said CN assistance information including informationdetermined in said CN based on a learning by said CN of a trafficpattern and/or a mobility pattern of said UE.

In an embodiment, CN assistance information provided by said CN to saidRAN for an UE is used in said RAN to adjust RAN parameters enabling tocontrol transitions between idle and connected state and/or powerconsumption in connected state for said UE.

In an embodiment, CN assistance information provided by said CN to saidRAN for an UE includes information capable of indicating a potential offrequent transitions between idle and connected state for said UE,and/or information capable of indicating a potential of low or nomobility for said UE, and/or information capable of indicating apotential of mobile originated only traffic or infrequent mobileterminated traffic for said UE.

In an embodiment, RAN assistance information is provided by said RAN tosaid CN for an UE.

In an embodiment, RAN assistance information provided by said RAN tosaid CN for an UE includes a current value of RAN parameters enabling tocontrol transitions between idle and connected state and/or powerconsumption in connected state for said UE.

In an embodiment, RAN assistance information provided by said RAN tosaid CN for an UE is used in said CN to assist in determining CNassistance information.

In an embodiment, RAN parameters enabling to control transitions betweenidle and connected state and/or power consumption in connected state foran UE include at least one of: an RRC Inactivity Timer, and a DRX Cycle.

In an embodiment, CN assistance information provided by said CN to saidRAN for an UE and indicating a potential of frequent transitions betweenidle and connected state for said UE, and/or a potential of low or nomobility for said UE and/or a potential of mobile originated onlytraffic or infrequent mobile terminated traffic, is used in said RAN toincrease an RRC Inactivity Timer and/or a DRX cycle for said UE.

In an embodiment, said method comprises:

-   -   a CN entity in charge of control plane learning a traffic        pattern of an UE by monitoring establishment and release of        signalling connections for said UE.

In an embodiment, said method comprises:

-   -   a CN entity in charge of control plane learning a traffic        pattern of an UE by monitoring the time elapsed between the        release of a last signalling connection and the establishment of        a subsequent signalling connection for said UE.

In an embodiment, said method comprises:

-   -   a CN entity in charge of control plane learning a traffic        pattern of an UE by detecting frequent transitions between idle        and connected states for said UE.

In an embodiment, said method comprises:

-   -   a CN entity in charge of control plane learning a traffic        pattern of an UE by monitoring whether or how frequently traffic        originates from the UE or/and the network.

In an embodiment, said method comprises:

-   -   a CN entity in charge of control plane learning a traffic        pattern of an UE by detecting UE that only or mainly utilizes        mobile originated communications.

In an embodiment, said method comprises:

-   -   a CN entity in charge of user plane learning a traffic pattern        of an UE by detecting an application type used by said UE.

In an embodiment, said method comprises:

-   -   a CN entity in charge of user plane learning a traffic pattern        of an UE by detecting inter-packet arrival time for said UE.

In an embodiment, said method comprises:

-   -   a CN entity in charge of control plane learning a mobility        pattern of an UE by monitoring mobility events for said UE over        time.

In an embodiment, said method comprises:

-   -   a CN entity in charge of control plane learning a mobility        pattern of an UE based on subscription data indicating a        mobility profile of said UE, such as static or nomadic user.

In an embodiment, said method comprises:

-   -   a CN entity in charge of control plane notifying CN assistance        information for an UE to a RAN entity.

In an embodiment, said method comprises:

-   -   a CN entity in charge of control plane notifying to a RAN entity        CN assistance information for an UE and RAN assistance        information previously received by said CN entity from a last        RAN entity for said UE.

In an embodiment, said method comprises:

-   -   a CN entity in charge of control plane notifying CN assistance        information for an UE to a RAN entity in a message sent during a        Service Request procedure for said UE, such as in S1-AP S1        Initial Context Setup Request sent by MME to eNB in EPS.

In an embodiment, said method comprises:

-   -   a CN entity in charge of control plane notifying to a RAN entity        CN assistance information for an UE and RAN assistance        information previously received by said CN entity from a last        RAN entity for said UE, in a message sent during a Service        Request procedure for said UE, such as in S1-AP S1 Initial        Context Setup Request sent by MME to eNB in EPS.

In an embodiment, said method comprises:

-   -   a RAN entity, notified of CN assistance information for an UE,        adjusting RAN parameters enabling to control transitions between        idle and connected state and/or power consumption in connected        state for said UE, based on said CN assistance information.

In an embodiment, said method comprises:

-   -   a RAN entity, notified of CN assistance information and RAN        assistance information for an UE, adjusting RAN parameters        enabling to control transitions between idle and connected state        and/or power consumption in connected state for said UE, based        on said CN assistance and RAN assistance information.

In an embodiment, said method comprises:

-   -   a RAN entity notifying RAN assistance information for an UE to a        CN entity in charge of control plane.

In an embodiment, said method comprises:

-   -   a RAN entity notifying RAN assistance information for an UE to a        CN entity in charge of control plane, in a message sent during a        signalling connection release procedure for said UE, such as in        S1-AP S1 UE Context Release Complete sent by eNB to MME in EPS.

In other aspects, there are provided entities configured for carryingout such method, said entities including in particular (though notexclusively), RAN entity (such as eNB for E-UTRAN, or RNC for UMTS), CNentity in charge of control plane (such as MME for EPC, or SGSN forUMTS), CN entity in charge of user plane (such as Serving Gateway S-GWor PDN Gateway P-GW for EPC, or GGSN for UMTS).

A person of skill in the art would readily recognize that steps ofvarious above-described methods can be performed by programmedcomputers. Herein, some embodiments are also intended to cover programstorage devices, e.g., digital data storage media, which are machine orcomputer readable and encode machine-executable or computer-executableprograms of instructions, wherein said instructions perform some or allof the steps of said above-described methods. The program storagedevices may be, e.g., digital memories, magnetic storage media such as amagnetic disks and magnetic tapes, hard drives, or optically readabledigital data storage media. The embodiments are also intended to covercomputers programmed to perform said steps of the above-describedmethods.

1-21. (canceled)
 22. A method for optimization of network signallingload and/or User Equipment power consumption in an Evolved Packet SystemEPS wherein an User Equipment UE has access to a network comprising aCore Network CN accessed by a Radio Access Network RAN, a method whereinCN assistance information is provided by a Mobility Management EntityMME to a eNodeB for an UE, said CN assistance information includinginformation determined in said MME based on a learning of a trafficpattern and/or a mobility pattern of said UE, and said CN assistanceinformation is used in said eNodeB to adjust RAN parameters enabling tocontrol transitions between idle and connected state and/or powerconsumption in connected state for said UE.
 23. A method according toclaim 22, wherein said CN assistance information includes informationcapable of indicating a potential of frequent transitions between idleand connected state for said UE, and/or information capable ofindicating a potential of low or no mobility for said UE, and/orinformation capable of indicating a potential of mobile originated onlytraffic or infrequent mobile terminated traffic.
 24. A method accordingto claim 22, wherein said RAN parameters include at least one of: an RRCInactivity Timer, and a DRX Cycle.
 25. A method according to claim 23,wherein CN assistance information indicating a potential of frequenttransitions between idle and connected state for said UE, and/or apotential of low or no mobility for said UE and/or a potential of mobileoriginated only traffic or infrequent mobile terminated traffic, is usedin said RAN to increase an RRC Inactivity Timer and/or a DRX cycle forsaid UE.
 26. A method according to claim 22, wherein said CN assistanceinformation includes information determined in said MME based on alearning of a traffic pattern of said UE, comprising: said MME learningsaid traffic pattern by monitoring establishment and release ofsignalling connections for said UE.
 27. A method according to claim 22,wherein said CN assistance information includes information determinedin said MME based on a learning of a traffic pattern of said UE,comprising: said MME learning said traffic pattern by monitoring thetime elapsed between the release of a last signalling connection and theestablishment of a subsequent signalling connection for said UE.
 28. Amethod according to claim 22, wherein said CN assistance informationincludes information determined in said MME based on a learning of atraffic pattern of said UE, comprising: said MME learning said trafficpattern by detecting frequent transitions between idle and connectedstates for said UE.
 29. A method according to claim 22, wherein said CNassistance information includes information determined in said MME basedon a learning of a traffic pattern of said UE, comprising: said MMElearning said traffic pattern by monitoring whether or how frequentlytraffic originates from the UE or/and the network.
 30. A methodaccording to claim 22, wherein said CN assistance information includesinformation determined in said MME based on a learning of a trafficpattern of said UE, comprising: said MME learning said traffic patternby detecting UE that only or mainly utilizes mobile originatedcommunications.
 31. A method according to claim 22, wherein said CNassistance information includes information determined in said MME basedon a learning of a mobility pattern of said UE, comprising: said MMElearning said mobility pattern by monitoring mobility events for said UEover time.
 32. A method according to claim 31, wherein: said mobilityevents include handovers.
 33. A method according to any of claims 22,wherein said CN assistance information includes information determinedin said MME based on a learning of a mobility pattern of said UE,comprising: said MME learning said mobility pattern based onsubscription data indicating a mobility profile of said UE, such asstatic or nomadic user.
 34. A method according to any of claims 22,comprising: said MME notifying to said eNodeB CN assistance informationfor said UE.
 35. A method according to claim 35, comprising: said MMEnotifying to said eNodeB CN assistance information for said UE, in amessage sent during a Service Request procedure.
 36. A method accordingto any of claims 22, comprising: said MME notifying to said eNodeB CNassistance information for said UE in a S1-AP S1 Initial Context SetupRequest.
 37. A method according to any of claims 22, comprising: saideNodeB, notified by said MME of CN assistance information, adjustingsaid RAN parameters based on said CN assistance information.
 38. AMobility Management Entity MME, configured to: provide Core Network CNassistance information for a User Equipment UE to a eNodeB, said CNassistance information including information determined in said MMEbased on a learning of a traffic pattern and/or a mobility pattern ofsaid UE.
 39. A MME according to claim 38, configured to: notify said CNassistance information in a message sent during a Service Requestprocedure for said UE.
 40. A MME according to claim 38, configured to:notify said CN assistance information in a message S1-AP S1 InitialContext Setup Request.
 41. A eNodeB, configured to: receive Core NetworkCN assistance information for a User Equipment UE from a MobilityManagement Entity MME, use said CN assistance information to adjust RANparameters enabling to control transitions between idle and connectedstate and/or power consumption in connected state for said UE.
 42. AeNodeB according to claim 41, configured to: receive CN assistanceinformation for an UE in a message sent during a Service Requestprocedure for said UE.
 43. A eNodeB according to claim 41, configuredto: receive said CN assistance information in a message S1-AP S1 InitialContext Setup Request.